Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual classe tem cbon-fm-23 como identificador?
 ###Tabelas: CREATE TABLE railway_stations_currently_in_use (railway_stations_currently_in_use_id AUTO_INCREMENT PRIMARY KEY, Station (and code) VARCHAR, Managed by VARCHAR, Lines served VARCHAR, Station users 2007/8 INT, Station users 2008/9 VARCHAR, Year opened VARCHAR, Platforms VARCHAR, Borough VARCHAR) CREATE TABLE team_players_drafted_in_the_nba (team_players_drafted_in_the_nba_id AUTO_INCREMENT PRIMARY KEY, Year INT, Round INT, Pick INT, Player VARCHAR, NBA Team VARCHAR) CREATE TABLE past_and_current_programs (past_and_current_programs_id AUTO_INCREMENT PRIMARY KEY, Year INT, Program Title VARCHAR, Placement VARCHAR, Score INT, Class VARCHAR) CREATE TABLE transmitters (transmitters_id AUTO_INCREMENT PRIMARY KEY, City of license VARCHAR, Identifier VARCHAR, Frequency VARCHAR, Power VARCHAR, Class VARCHAR, RECNet VARCHAR) CREATE TABLE six-man_elimination_tag_team_match (six-man_elimination_tag_team_match_id AUTO_INCREMENT PRIMARY KEY, Elimination VARCHAR, Wrestler VARCHAR, Eliminated by VARCHAR, Elimination Move VARCHAR, Time VARCHAR)  
SELECT Class FROM transmitters WHERE Identifier = cbon-fm-23